How to operate a vehicle electric drive system

Abstract

The present invention relates to a method for operating an electric drive system (1) for a vehicle, comprising at least one electric three-phase machine (2), a battery (3) that supplies electric energy to the electric three-phase machine (2), and an inverter (4), wherein the electric three-phase machine (2) is electrically connected to or connected to the battery (3) through the inverter, the neutral point (7) of the electric three-phase machine (2) is electrically connected to or connected to the positive connection part (8) of the DC charging connection part of the electric drive system (1), and the negative potential line (6) of the battery (3) is electrically connected to or connected to the negative connection part (9) of the DC charging connection part of the electric drive system (1). Here, the neutral point (7) of the electric three-phase machine (2) is electrically connected to or connected to the positive terminal (8) of the DC charging connection of the electric drive system (1) through the first switch (S1), the negative potential line (6) of the battery (3) is electrically connected to or connected to the negative terminal (9) of the DC charging connection of the electric drive system (1) through the second switch (S2), and the positive terminal (8) of the DC charging connection of the electric drive system (1) is electrically connected to or connected to the tap of the intermediate circuit capacitor (C1) through the third switch (S3), and accordingly, is electrically connected to or connected to the positive potential line (5).

Description

Technology Field

[0001] The present invention relates to a method for operating an electric drive system for a vehicle having the features of the preamble of claim 1. Background Technology

[0002] As described in German Patent DE 10 2018 000 488 A1, an electric drive system for a vehicle and a method for driving the same are known in the prior art. The electric drive system comprises at least one electric three-phase machine and a battery that supplies electric energy to the electric three-phase machine. The electric three-phase machine is electrically connected to or connected to the battery through an inverter, the neutral point of the electric three-phase machine is electrically connected to or connected to the positive terminal of the DC charging connection of the electric drive system, and the negative terminal of the battery is electrically connected to or connected to the negative terminal of the DC charging connection of the electric drive system.

[0003] In addition, German Patent DE 10 2018 124 789 A1 discloses a charging device for a vehicle designed to have an electric drive motor, comprising an inductance and a drive converter. The drive converter converts the DC voltage of the battery for the electric drive motor in the vehicle's driving mode, and the inductance is used as a boost converter together with the drive converter for the battery's charging mode. Furthermore, the charging device is provided with a switching unit to connect the charging source directly to the battery or through the boost converter in the charging mode. The problem to be solved

[0004] The objective of the present invention is to provide a method for operating an electric drive system of a vehicle that is improved compared to the prior art.

[0005] According to the present invention, this objective is achieved by a method for operating an electric drive system for a vehicle having the features of claim 1.

[0006] The preferred configuration of the present invention is the subject of the dependent claim.

[0007] An electric drive system for a vehicle comprises at least one electric three-phase machine, a battery that supplies electric energy to the electric three-phase machine, and an inverter, through which the electric three-phase machine can be electrically connected to or is connected to the battery, the neutral point of the electric three-phase machine can be electrically connected to or is connected to the positive terminal of the DC charging connection of the electric drive system, and the negative potential line of the battery can be connected to or is connected to the negative terminal of the DC charging connection of the electric drive system.

[0008] The neutral point of the electric three-phase machine is electrically connected to or connected to the positive terminal of the DC charging connection of the electric drive system through a first switch, the negative potential line of the battery is electrically connected to or connected to the negative terminal of the DC charging connection of the electric drive system through a second switch, and the positive terminal of the DC charging connection of the electric drive system is electrically connected to or connected to the tap of the intermediate circuit capacitor through a third switch, and accordingly, is electrically connected to or connected to the positive potential line through this.

[0009] In a method for operating an electric drive system according to the present invention, when battery charging from an external DC energy source is not to be performed, all three switches are opened, and in order to charge the battery from an external DC energy source where the supplied DC voltage matches the battery's nominal voltage, the first switch and the second switch are closed and the third switch is opened, and in order to charge the battery from an external DC energy source where the supplied DC voltage is lower than the battery's nominal voltage, all three switches are closed.

[0010] According to the described solution, battery charging becomes possible through the inductance of an electric three-phase machine. In this case, it is possible to charge the battery from an external DC energy source where the supplied DC voltage matches, for example, the battery's nominal voltage of 800 V, as well as from an external DC energy source where the supplied DC voltage is only, for example, 400 V, which is lower than the battery's nominal voltage of 800 V. Since minimal effort is required for this solution, it can be implemented cost-effectively. means of solving the problem

[0011] As described above, the first and second switches are closed and the third switch is opened so that the battery is charged from an external DC energy source where the supplied DC voltage matches the battery's nominal voltage. Through the closed first switch, the neutral point is electrically connected to the positive terminal of the DC charging connection and, consequently, to the positive terminal of the external DC energy source when it is connected thereto. Through the closed second switch, the negative potential line is electrically connected to the negative terminal of the DC charging connection and, consequently, to the negative terminal of the external DC energy source when it is connected thereto. Thus, when an external DC energy source where the supplied DC voltage matches the battery's nominal voltage is connected to the DC charging connection, the neutral point and the negative potential line are electrically connected to the external DC energy source. Additionally, to directly electrically connect the battery to the external DC energy source, all transistors in a specific area of ​​the inverter, particularly the upper area, are continuously switched. As a result, the battery is charged with a DC voltage supplied from an external DC energy source corresponding to the battery's nominal voltage.

[0012] As previously described, all three switches are closed so that the battery is charged from an external DC energy source, where the supplied DC voltage is lower than the battery's nominal voltage, for example, only 400 V. Accordingly, the neutral and negative potential lines are electrically connected to the DC charging connection and, consequently, to the external DC energy source when connected thereto. All transistors of the inverter operate in pulse width modulation and, combined with the inductance of the electric three-phase machine, form a step-up converter that steps up the low DC voltage supplied from the external DC energy source to the battery voltage level, i.e., a nominal voltage of, for example, 800 V. Alternatively, only the transistors in other regions of the inverter, particularly the lower region, are clocked, so that current flow occurs through the freewheeling diode in the upper region of the inverter rather than through the transistors in the upper region of the inverter. Additionally, as previously described, the intermediate circuit capacitor can preferably be designed with two components. Effects of the invention

[0013] Due to this arrangement, the center point of the capacitor is connected in parallel with the input of the DC voltage supplied from an external DC energy source, allowing it to be stabilized. Therefore, a separate input capacitor is not required for the charging mode.

[0014] In one possible embodiment, two intermediate circuit capacitors are provided that are electrically connected in series.

[0015] Embodiments of the present invention will be described in more detail below with reference to the drawings. Brief explanation of the drawing

[0016] FIG. 1 is a schematic diagram illustrating an electric drive system for a vehicle in a first switching state. FIG. 2 is a schematic diagram illustrating an electric drive system in a second switching state. FIG. 3 is a schematic diagram illustrating an electric drive system in a third switching state. Members that correspond to each other are indicated by the same drawing symbol in all drawings. FIGS. 1 to 3 schematically illustrate a vehicle electric drive system (1) in three switching states. Specific details for implementing the invention

[0017] The electric drive system (1) includes an electric three-phase machine (2), a battery (3) that supplies electric energy to the electric three-phase machine (2), and an inverter (4). Through this inverter, the electric three-phase machine (2) can be electrically connected to the battery (3) or is electrically connected as shown in FIGS. 1 to 3. To this end, the inverter (4) can be electrically connected to the battery (3) through a positive potential line (5) and a negative potential line (6), or is connected as shown in FIGS. 1 to 3, and can be electrically connected to the electric three-phase machine (2) through phase conductors (P1, P2, P3).

[0018] The inverter (4) has an electrical series circuit of two transistors (T11, T12, T21, T22, T31, T32) and two freewheeling diodes (D11, D12, D21, D22, D31, D32) that are electrically connected in parallel with each other and are electrically connected to a positive potential line (5) and a negative potential line (6), respectively. The phase conductors (P1, P2, P3) are electrically connected to a connection line between an electric three-phase machine (2) and a pair of electrically series-connected transistors (T11, T12, T21, T22, T31, T32) and electrically series-connected freewheeling diodes (D11, D12, D21, D22, D31, D32), respectively. The transistors (T11, T21, T31) and freewheeling diodes (D11, D21, D31) placed on the side of this junction point of the phase conductors (P1, P2, P3) form the upper region (OB) of the inverter in the present invention, and the transistors (T12, T22, T32) and freewheeling diodes (D12, D22, D32) placed on the other side of this junction point of the phase conductors (P1, P2, P3) form the lower region (UB) of the inverter in the present invention. The forward direction of the freewheeling diodes (D11, D12, D21, D22, D31, D32) is oriented in the direction of the positive potential line (5), respectively.

[0019] Additionally, the positive potential line (5) and the negative potential line (6) are electrically connected in series and electrically connected in parallel with the inverter (4) and two intermediate circuit capacitors (C1, C2). That is, the solution described herein includes an intermediate circuit capacitor divided into two intermediate circuit capacitors (C1, C2).

[0020] The neutral point (7) of the electric three-phase machine (2) is electrically connected to or connected to the positive connection part (8) of the DC charging connection part of the electric drive system (1) through a first switch (S1) designed specifically as a contactor, depending on whether the first switch (S1) is open or closed.

[0021] The negative potential line (6) is electrically connected to or connected to the negative connection part (9) of the DC charging connection part of the electric drive system (1) through a second switch (S2) designed specifically as a contactor, depending on whether the second switch (S2) is open or closed.

[0022] Additionally, the positive connection part (8) of the DC charging connection part of the electric drive system (1) is electrically connected to or connected to the connecting line of two intermediate circuit capacitors (C1, C2) depending on whether the third switch (S3), which is specifically designed as a contactor, is open or closed, and thus is electrically connected to the positive potential line (5) through the two intermediate circuit capacitors (C1, C2), in the present invention, through the first intermediate circuit capacitor (C1) when the third switch (S3) is closed.

[0023] According to the described solution, the battery (3) can be charged through the inductances (L1, L2, L3) of the electric three-phase machine (2). In this case, it is possible to charge the battery (3) from an external DC energy source where the supplied DC voltage (UDC) matches the nominal voltage (UBat) of the battery (3), for example, 800 V, as shown in FIG. 2, and it is also possible to charge the battery from an external DC energy source where the supplied DC voltage (UDC) is lower than the nominal voltage (UBat) of the battery (3), as shown in FIG. 3. Since minimal effort is required for this solution, it can be implemented cost-effectively.

[0024] In FIG. 1, all three switches (S1, S2, S3) are open. This switching state is preferably always provided when charging from an external DC energy source should not be performed or should not be performed yet. Because the positive terminal (8) and negative terminal (9) of the DC charging connection are electrically disconnected from the rest of the electric drive system (1), particularly the battery (3), inverter (4), and electric three-phase machine (2) by the open switches (S1, S2, S3), there is no risk of a person coming into contact with the high nominal voltage of the battery (3) and the resulting health-threatening nominal voltage (UBat) through the DC charging connection. For example, if the DC voltage (UDC) is already applied to the DC charging connection by being electrically connected to an external DC energy source, the battery (3) is not charged by the external DC energy source even if the switches (S1, S2, S3) are open.

[0025] This switching state is also provided for the vehicle's driving mode. During the driving mode, the electric three-phase machine (2) receives electrical energy from the battery (3) through the inverter (4).

[0026] In FIG. 2, the first switch (S1) and the second switch (S2) are closed, and the third switch (S3) is open. This switching state is provided to charge the battery (3) from an external DC energy source, such that the supplied DC voltage (UDC) matches the nominal voltage (UBat) of the battery (3), for example, 800 V. Through the closed first switch (S1), the neutral point (7) is electrically connected to the positive terminal (8) of the DC charging connection and, accordingly, to the positive terminal of the external DC energy source when connected thereto. Through the closed second switch (S2), the negative potential line (6) is electrically connected to the negative terminal (9) of the DC charging connection and, accordingly, to the negative terminal of the external DC energy source when connected thereto. Accordingly, when an external DC energy source is connected to the DC charging connection, the supplied DC voltage (UDC) matches the nominal voltage (UBat) of the battery (3), for example, 800 V, the neutral point (7) and the negative potential line (6) are electrically connected to the external DC energy source. Additionally, to directly electrically connect the battery (3) to the external DC energy source, all transistors (T11, T21, T31) in a specific area of ​​the inverter (4), particularly the upper area (OB), are continuously switched. As a result, the battery (3) is charged with the DC voltage (UDC) supplied from the external DC energy source corresponding to the nominal voltage (UBat) of the battery (3).

[0027] In FIG. 3, all three switches (S1, S2, S3) are closed. This switching state is provided to charge the battery (3) from an external DC energy source, where the supplied DC voltage (UDC) is smaller than the nominal voltage (UBat) of the battery (3), for example, 800 V. For example, the DC voltage (UDC) supplied from the external DC energy source is 400 V. Through the closed first switch (S1), the neutral point (7) is electrically connected to the positive terminal (8) of the DC charging connection and, accordingly, to the positive terminal of the external DC energy source when connected thereto. Through the closed second switch (S2), the negative potential line (6) is electrically connected to the negative terminal (9) of the DC charging connection and, accordingly, to the negative terminal of the external DC energy source when connected thereto. Additionally, when the positive terminal (8) of the DC charging connection unit and, accordingly, an external DC energy source is connected thereto through the closed third switch (S3), the positive terminal is electrically connected to two intermediate circuit capacitors (C1, C2), and accordingly, is electrically connected to the positive potential line (5) through one of the two intermediate circuit capacitors (C1, C2), in the present invention, the first intermediate circuit capacitor (C1).

[0028] When a DC energy source outside the vehicle is connected to a DC charging connection where the supplied DC voltage (UDC) is smaller than, for example, the nominal voltage (UBat) of the battery (3) of 800 V, the neutral point (7) and the negative potential line (6) are electrically connected to the DC energy source outside the vehicle, and additionally, the positive potential line (5) is electrically connected to the DC energy source outside the vehicle through the connection line of the two intermediate circuit capacitors (C1, C2) and, accordingly, through one of the two intermediate circuit capacitors (C1, C2), in the present invention, the first intermediate circuit capacitor (C1). All transistors (T11, T12, T21, T22, T31, T32) of the inverter (4) are operated in pulse width modulation and combined with the inductances (L1, L2, L3) of the electric three-phase machine (2) to form a boost converter that boosts a low DC voltage (UDC) supplied from an external DC energy source to the battery (3) voltage level, i.e., a nominal voltage (UBat) of 800 V. Alternatively, only the transistors (T12, T22, T32) of another region of the inverter (4), in this invention the lower region (UB), are clocked so that current flow is made through the freewheeling diodes (D11, D21, D31) of the upper region (OB) of the inverter (4) rather than through the transistors (T11, T21, T31) of the upper region (OB) of the inverter (4). Additionally, as previously mentioned, the intermediate circuit capacitor is designed with two components in the form of two intermediate circuit capacitors (C1, C2). Due to this arrangement, the center point of the capacitor is connected in parallel with the input of the DC voltage (UDC) supplied from an external DC energy source, thereby stabilizing it. Therefore, a separate input capacitor is not required for the charging mode. Explanation of the symbols

[0029]

Claims

Claim 1 As a method of operating an electric drive system (1) of a vehicle, the electric drive system (1) comprises an electric three-phase machine (2), a battery (3) that supplies electric energy to the electric three-phase machine (2), and an inverter (4), wherein the electric three-phase machine (2) can be electrically connected to the battery (3) through the inverter, the neutral point (7) of the electric three-phase machine (2) can be electrically connected to the positive connection part (8) of the DC charging connection part of the electric drive system (1), the negative potential line (6) of the battery (3) can be electrically connected to the negative connection part (9) of the DC charging connection part of the electric drive system (1), - the neutral point (7) can be electrically connected to the positive connection part (8) through a first switch (S1), - the negative potential line (6) can be electrically connected to the negative connection part (9) through a second switch (S2), and - the positive connection part (8) can be electrically connected to the intermediate circuit capacitor (C1) through a third switch (S3). A method for operating an electric drive system capable of electrically connecting to a tap and thereby electrically connecting to the positive potential line (5) of the battery (3), wherein the positive potential line (5) of the battery (3) is electrically connected to the positive connection part of the inverter (4), wherein when the battery (3) is not charged from a first DC energy source outside the vehicle, the first switch (S1), the second switch (S2), and the third switch (S3) are all opened, wherein to charge the battery (3) from a second DC energy source outside the vehicle where the supplied DC voltage (UDC) matches the nominal voltage (UBat) of the battery (3), the first switch (S1) and the second switch (S2) are closed and the third switch (S3) is opened, wherein to charge the battery (3) from a third DC energy source outside the vehicle where the supplied DC voltage (UDC) is smaller than the nominal voltage (UBat) of the battery (3), the first switch (S1) and the second When both the switch (S2) and the third switch (S3) are closed,Method of operating an electric drive system. Claim 2 A method for operating an electric drive system, wherein, in claim 1, the intermediate circuit capacitor is composed of two intermediate circuit capacitors (C1, C2) electrically connected in series.

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